Electron-discharge apparatus



July 21 1925.

J. C. WARNER ELECTRON DISCHARGE APPARATUS Filed July 11, 1924 Fig. l.

Inventor- I John C. X/ar'ner',

His Attorney.

Patented my 21-; 1925.

UNITED STATES 1,546,875 PATENT OFFICE.

JOHN G. WARNER, OF- SGHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC! COMPANY, A CORPORATION OF NEW YORK.

ELECTRON-DISCHARGE APPARATU S.

Application filed July 11, 1924. Serial No. 725,483.

To all whovri z't may concern:

Be it known that I, JOHN C. WARNER, a

citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Electron- Discharge Apparatus, of which the following is a specification.

My present invention relates to electron discharge apparatus'and more particularly to devices of the thermionic type having at least four electrodes.

. One, of the objects of my invention is to provide a'new and improved circuit organ-- ization which may be used to advantage with four electrode devices.

In connection with electron discharge devices of the thermionic type having a grid for controlling the flow of current between cathode and anode, it has been proposed to employ a second grid between the cathode and control grid, and to impress upon this second grid a constant positive potential somewhat lower than that of the anode. A grid used inthis way is commonly known as a space charge grid. The purpose of this grid is to lower the impedance between the cathode and a ode. It has been observed that the curren flowing to this space charge grid varies in the opposite way from the manner in which the current to the anode varies when acted upon by the control grid.

That is, as the current to the anode increases the current to the space charge grid decreases, and vice versa.

A further object of my invention is to provide means for taking advantage of this secondary variation of the current to the space charge grid to increase the amount of amplification which may be obtained.

Une of the difiiculties encountered in the use of three electrode amplifiers lies in the fact that there is always a direct current fiowing in the plate or output circuit which is much greater than the amplified current. When a unidirectional current is to, be amplified it is usually necessary to balance out this initial direct current by some combination of resistance and an auxiliary battery before it is possible to utilize the amplified current. Still another object of my invention is to overcome this disadvantage and provide a circuit arrangement in which there will normally be no direct current flowing in the load circuit.

The novel features which I believe to be characteristic of my invention are set forth w1th particularity in the appended claims. My invention itself, however, both as to its organization and method of operation will best be understood by reference to. the followlng description taken in connection with the accompanying drawing in which Fig. 1 shows a circuit arrangement whereby my invention may be carried into efi'ect, and Fig. 2 shows a modification especially adapted for the amplification of alternating current.

I have indicated in the drawing an electron discharge device 1 having the usual electron emitting cathode 2 and anode 3, a control grid 4 and a space charge grid 5. In practice, devices suitable for carrying out my invention may most conveniently be made in concentric form, the cathode being centrally located, the space charge grid 5 closely surrounding the cathode and the control grid 4 and anode 3 surrounding the cathode and space charge grid.

In Fig. 1, I have shown a resistance 6 in the control grid or input circuit across which the voltage to be amplified is introduced. The value of this resistance will depend upon the characteristics of the circuit supplying the voltage to be amplified and the resistance 6 may be unnecessary if the feeding circuit provides a conductive connection between control grid and cathode. An impedance made of two ohmic resistances f? and 8 has one terminal connected directly to the anode 3 and its other terminal connected to the space charge grid 5 through an ohmic resistance 9. lihe cathode 2 is connected through a source of current 10' to a point between the two parts 7 and 8 of the impedance. Aload circuit containing any desired form of current indicating or utilizing device 11 is also connected to the terminals of the impedance.

In the operation of the system the values of resistances 7, 8 and 9 are so adjusted that when no voltage is applied across resistance 6, the currents flowing through 7 and 8 are of such value that the voltage drops in the two are equal. Points 12 and 13 will then be at the same potential and no current will flow in the load circuit. 7

In the absence of the resistance 9, the potential difference between the space charge grid 5 and cathode 2 will be the same as the potential difference between the anode 3 and cathode 2. Ordinarily the space charge grid should be at a lower potential than the anode and the value of resistance 9 is chosen to bring the potential of space charge grid 5 to the proper value. This resistance 9 together with resistance 8 tends to raise the mutual conductance of the device above what it would be if the space charge grid were connected. directly to battery 10.

When the potential of the control grid is changed by the application of voltage to the input circuit the anode current and the current to the space charge gridfvary but in opposite directions. The result, in detail, is as follows :Assuming that the potential of the control grid is made positive with respect to its initial value, the anode current increases and the space charge grid current decreases. The voltage drop across 7 increases and the voltage drop across 8 decreases. Consequently the potential of point 12 falls and'that of point 13 rises. Hence a potential difference is produced between points 12 and 13 which will cause current to flow in the load circuit. When the potential of the control grid is made negative this action, of course, takes place in the same way but in the opposite direction.

The system which I have described is applicable for the amplification of variable direct current or alternating current. In Fig. 2 I have shown a system which is particularly adapted for the amplification of alternating current. In this case the current to be amplified is impressed upon the input circuit by means of a transformer 14 and the impedance in the output circuit is in the form of a reactance made up of two parts 15 and 16 of high impedance. These reactances are preferably wound upon a common core. By this expedient the direct current magnetization can be completely neutralized as the direct current will flow through the two coils in opposite directions. The system of Fig. 2 like that of Fig. 1 may be so adjusted that when no voltage is applied to the'control grid points 12 and 13 will be at the same potential and hence there will be no flow of direct current-in the load circuit. I

While I have shown and described only two embodiments of my invention it is apparent that many modifications in the circuit arrangements employed may be made without departing from the scope thereof as set forth in the appended claims.

What I claim as new and desire .to secure by Letters Patent of the United States is:

1. The combination with an electron discharge devicehaving an electron emitting cathode, an alflodejand two grids interposed between cathodeumd anode, of an input cir cuit connected to one of said grids, and an impedance having its terminals connected to the anode and the second grid, an interamas-2e mediate point in said impedance being con- 2. The combination with an electron dis charge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, of an input circuit connected to one of said grids, and an impedance having its terminals connected to the anode and the second grid, an intermediate point in said impedance being con nected to the cathode through a source of 'current, the constants of the circuit arrangement being so chosen that when no potential is applied to the input circuit the two terminals of the impedance are at substantially the same potential.

3. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, of an input circuit connected to one of said grids, and an impedance having its terminals connected to the anode and the second grid, an intermediate point in said impedance being connected to the cathode through a source of current, and a load circuit connected to the terminals of said impedance.

4. The combination with an electron dis charge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, of an input cir- -is applied to the input circuit the two terminals of the impedance are at substantially the same potential, and a load circuit con-.

nected to the terminals of said impedance.

5. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, of an input circuit connected to the grid nearest the anode, and an impedance having its terminals connected to the anode and the grid nearest the cathode, an intermediate point in said impedance being connected to the cathode through a source of current.

6. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, of an input circuit connected to the grid nearest the anode,

and an impedance havin its terminals conput circuit the two terminals of t he impedance areat substantially the same poten- V tial.-

7 L The c mbination with an electron-dis charge device'having an electron emlttmg cathode, an anode and two grids interposed between cathode and anode, of an input circuit connected to the grid nearest the anode,

and an inn edance having its terminals con nected to t e anode and the grid nearest the cathode, an intermediate point in said. 1mpedance being connected to the cathode through a source of current, and a load circuit connected to the terminals of said im pedance.

8. The combination Wltll' an electron discharge device having an electron emitting cathode,-an anode and twognds lnterposed between cathode and anode, of an input circuit connected to the grid nearest the anode,

' and an impedance having its terminals connected to tlie anode and the grid nearest the cathode, an intermediate point in said impedance being connected to the cathode through a source of currentfthe constants of the circuit arrangement being so chpsen that when no potential is applied to the input circuit-the two terminals of the impedance are at substantially the same P0116111 tial, and a load circuit connected to the terminals of said impedance.

9. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode of an input circuit connected to one of said grids and an impedance having one of its terminals connected directly tosaid anode and its other terminal connected 'to the second grid through an ohmic resistance, an intermediate point in said impedance being connected to the cathode through a source of current.

10. The combination with an electron dis-' charge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode of an input circuit connected to ,one of said grids and an impedancehaving one of its terminals connected directly to said anode and itsother, terminal connected tothe second I grid through an ohmic resistance, an intermediate point in said impedance being connected to the cathode through a. source of current, the constants of the circuit arrangement being so chosen that when no potential is applied to the input circuit the two terminals terminal connected to the second grid Q 1,540,875 I a through an ohmic resistance, an intermedi;

ate point in said impedance being connected to the cathode through a source of current, and aload circuit connected to the terminals'of said impedance.-

' 12. The combination with an electron dis charge device having an electron emittin cathode, an anode and two rids interposed between cathode and ano e of an input circuit connected to one of said grids and air iinpedance having one of its terminals connected directly to said anode and its other terminal connected to the second grid through an ohmic resistance, an intermediate point in said impedance being connected to the cathode through a source of'current, the constants of the circuit arrangement being so chosen that when no potential is applied to the input circuit the two terminals of the impedance are at substantially the same potential, and a load circuit connected to the terminals of said impedance.

13. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode of an input circuit connected to thegrid nearest the anode and an impedance having one of its terminals connected directly to said anode and its other terminal connected to the grid nearest the cathodethrough an ohmic resistance, an intermediate point in said impedance being connected I tothe cathode through a source of current.

14. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and' anode of an input circuit connected to the grid nearest the anode and an impedance having one of its terminals connected directly to said anodeand its other terminal connected to the grid nearest the cathode through an ohmic resistance, an intermediate point in said impedance being connected to the cathode through a source of current, the constants of the circuit ar rangement being so chosen that when no potential is applied to the input circuit the two terminals of the impedance are at substantially the same potential.

15. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode of an input circuit'ponnected to the grid nearest the anode and an impedance having one of its terminals connected directly to .said anode and its other terminal connected to the grid nearest the cathode through an ohmic resistance, an intermediate lpoint in said im-.

.pedance being connected to the cathode through a source of current and a load circuit connected to the terminals of said impedance.

source of current, the constants of the circuit arrangement bein so chosen that when no potential is applied to the input circuit the two terminals of the impedance are at substantially the same potential, and a load cii-cuit connected to the terminals of said impedance.

In witness whereof, I have hereunto set nfy hand this 8th day of July, 1924.

JOHN G. WARNER. 

